We are currently analyzing whole exome sequencing (WES) with appropriate follow up to identify important genetic factors associated with Cushing's disease (CD) and related abnormal physical features. The ultimate goal is to identify a genetic variant or variants that cause CD. CD is a condition in which the pituitary gland produces inappropriately high levels of adrenocorticotropic hormone (ACTH). The ACTH stimulates the adrenal gland to produce excess cortisol, leading to clinical disease. CD is caused by ACTH secreting pituitary tumors. CD is a serious condition. It requires surgery to remove the tumor. The tumors sometimes recur in which case radiation or medical therapy is required which is not always successful. CD can cause a wide range of problems due to the high cortisol levels. These include diabetes, fractures, poor growth, and hypertension. CD can be fatal. Whole exome sequencing (WES) is a powerful tool for identifying important genetic variants associated with medical conditions. It is an efficient method of determining the genetic code (sequence) of all the regions in the genome that are translated into protein, the exons. The exons constitute about 1% of DNA, thus sequencing exons provides a large amount of information at a lower cost than sequencing the entire genome. Pediatric aged patients seen at NICHD with a confirmed diagnosis of CD are evaluated for this study. Those who have histopathologically confirmed disease in conjunction with DNA, hormonal documentation of the disease and complete clinical data are potential cases. Analysis comparing variants found in the cases with large control populations has been done. In addition, the data are being examined for copy number variants in the exons to determine if they play a role in Cushing's disease. Whole exome sequencing has now been performed on tumor tissue in patients where tumor tissue is available to determine if there are specific tumor-associated variants in the exome. These data have been analyzed in the same manner as the blood samples. In addition, samples from patients who have ectopic posterior pituitaries have been obtained and whole exome sequenced. The data have been screened using standard data sets to identify rare variants. Since the last report, the group has published on large genomic aberrations in corticotropinomas as a predictor of tumor aggressiveness and prognosis. We studied whether somatic copy number variants (CNVs)in pituitary tumors are related to progression and invasiveness. Chromosomal instability, involving 23% to 59% of the tumor genome, was noted in 5 of the 27 samples (18.5%). The patients with tumors showing chromosomal instability had similar clinical and biochemical characteristics to the remaining patients, except for tumor size, which was larger (median size 18 mm vs 5.5 mm, P = 0.005). Tumors with chromosomal instability were also associated with a higher rate of invasion of the cavernous sinus (P = 0.029). There was insufficient information on persistence or recurrence of CD to determine whether the risk was higher in those with chromosomal instability. In summary a subgroup of corticotropinomas demonstrates chromosomal instability that is associated with markers of aggressiveness of these adenomas. It appears that more genomic gains/losses in a few, rare corticotropinomas may predict poorer prognosis for pediatric patients with CD.